Slack cable stop for hoists



Feb. 5, 1935.

J. J. MIZER SLACK CABLE STOP FOR HOISTS Filed July 2, 1934 4Sheets-Sheet 1 ,7 Inl/enfg. 1921' Feb. 5, 1935. J MlZER 1,990,241

. SLACK CABLE VSTOPHFOR HOISTS Fil d July 2, 19:54 4 Sheets-Sheet 2ITurento r v onnejjs.

Feb. 5, 1935. J. J. MIZER SLACK CABLE STOP FOR HOISTS Filed July 2',1954 4 Sheets-Sheet 3 Inzfen'tar IH' $452301 .f/fiewr M Mm I. Am:

Feb. 5,1935. J J MlZER 1,990,241

SLA CK CABLE STOP FOR HOISTS Filed July 2, 1934 4 Sheets-Sheet 4 19Infle ntan 1/ Y lis a5 w H M W Patented Feb. 5, 1935 SLACK CABLE STUPFUR- HGESTS v Joseph J. Mizer, Racine, Wis, assignor to WalkerManufacturing Company, Racine, Wis, a cor poration of WisconsinApplication July 2, 1934, Serial No. 733,429

16 Claims.

This invention relates to certain new and useful improvements in a slackcable stop mechanism and more particularly to such a stop mechanismdesigned for use with hoisting mechanism of the 5 type adapted to bodilyelevate an automobile so as to permit easy access to the under portionsof the chassis.

Briefly described, a hoisting mechanism of the type to which thisinvention is preferably applied, embodies a plurality of separateupright posts positioned adjacent the corners of a clear space intowhich the automobile may be run. An open carriage structure adapted tosupport the automobile is guided for vertical movement between theposts, the carriage preferably being provided with guides engaging theseveral posts. The means for raising and lowering the carriage comprisesa winding mechanism operated by a reversible electric motor supportedadjacent the upper end of one of the posts.

Cables extend from the winding mechanism to the several corner portionsof the carriage, the carriage being suspended from these cables at alltimes so as to normally keep the cables taut.

The motor is controlled by means of a switch mechanism, preferablysupported adjacent the upper end of one of the posts, the switchcomprising a memher which is swung through a certain arc in onedirection from a neutral position to cause the motor to elevate thecarriage, the member being swung through a similar arc in the oppositedirection from neutral position to reverse the motor and cause thecarriage to be lowered. A hoisting mechanism of this general typeprovided with numerous detailed improvements and safety devices notherein specifically disclosed or referred to, is disclosed more indetail and claimed in the patent to Willard T. Walker, 1,958,026,granted May 8, 1934.

The present invention is concerned more particularly with a stopmechanism adapted to automatically throw the control switch to neutralposition and thus stop the motor and winding mechanism whenever one ofthe cables becomes slack for any reason, for example when the weight ofthe carriage is no longer suspended from the cables.

A vertically shiftable device positioned stop the motor.

The cable-controlled portion of the stop mechanism comprises a memberpivotally mounted adjacent the shiftable member and provided with an armwhich is adapted to be moved into engagement with the shiitable memberto actuate the same and throw the switch to neutral position. Thispivoted member also comprises an arm carrying a roller which is alwaysheld in engagement with the cable by means of a spring which tends toswing the pivoted member in a direction to actuate the stop device. Aslong as the cable is taut, the pivoted member will be held ininoperative position, but as soon as the cable becomes slack the springwill swing the member so as to actuate the vertically shiftable deviceand throw the switch to neutral position.

The principal object of this invention is to provide an improvedautomatic slack cable stop mechanism of the type briefly describedhereinabove and disclosed more in detail in the specifications whichfollow.

Other objects and advantages of this invention will be more apparentfrom the following detailed description of one approved form of deviceconstructed and operating according to the principles of this invention.

In the accompanying drawings:

Fig. l is a side elevation of the hoisting apparatus in elevatedposition, the corner-posts being partially broken away intermediatetheir ends.

Fig. 2 is an enlarged elevation of the operating assembly shown in theupper left-hand portion of Fig 1, the view being taken from the oppositeside, that is within the end portion of the hoisting mechanism, andcertain of the parts being broken away.

Fig. 3 is an enlarged elevation looking from the left at the assemblyshown in Fig. 2.

Fig. 4 is a perspective view of the slack cable controlled portion ofthe stop mechanism. The spring actuated portion of this mechanism isshown in its released position in this view, whereas in Figs. 1, 2 and 3it is shown in the normal position in which it is held by the tautcable.

Fig. 5 is a vertical section through a portion of the switch mechanism,showing the device for holding the switch yieldably in each of its offand on positions.

Figs. 6, '7, 8 and 9 are similar partial side elevations showing thestop mechanism in several different operative positions.

Fig. 10 is a perspective view of the longitudinally shiftable cam-platefor throwing the switch to stop position.

The apparatus may be described in general as comprising a fixedsupporting frame indicated generally at A, a vertically movable carriageB guided within frame A, a cable hoisting mechanism indicated generallyat C which is mounted on the frame A and from which the carriage B issuspended, a driving motor D, the switch mechanism E for controlling themotor, and the stop mechanism indicated generally at F, this stopmechanism being operable either by the limitstop mechanism G or by theslack-cable controlled mechanism indicated at H which forms (incombination with the other apparatus herein disclosed) the particularsubject matter of this invention.

The frame A comprises four similar upright posts or standards 1,preferably in the form of hollow metallic pipe sections which aremounted outside of but adjacent four corners of a rectangular clearspace suitable for receiving the automobile or other vehicle to behoisted. These posts are fixedly supported in any suitable manner,preferably by embedding the lower end portions thereof in the groundorother supporting foundation, indicated at 2. The upper ends of the pairof posts at each side of the frame are connected by a horizontal bracemember 3, and the upper end portions of the two posts at one end of theframe (the left-hand end in Fig. 1) are connected by a non-rotatableshaft 4 (see Figs. 2 and 3).

The carriage B may be of any suitable construction for supporting theautomobile so as to permit as free access as possible to the underportions of the car. In the example here shown the carriage comprises apair of longitudinally extending beams 5 adapted to engage beneath thefront axle 6 and some portions 7 of the rear axle assembly so as tosupport the automobile. Alternatively, a pair of runways may be usedspaced apart so as to receive the four wheels of the automobile. Theselongitudinal carriage members are connected adjacent the posts 1 bytransversely extending beams 8 provided at their ends with guide membersengaging the respective posts. As here shown, these guides are in theform of loops 9 which engage loosely about the posts while the carriageis in normal horizontal position but which will bind against the poststo support the carriage should some portion of the cable hoistingmechanism fail so as to permit the carriage to cant in any directionfrom its normal horizontal position.

The winding mechanism C comprises a pair of similar winding drums 10,one positioned adjacent the upper end of each of the posts 1 at one endof the frame,the drums being connected by the torque tube 11 mountedaround fixed shaft 4 so that the drums will be supported to rotate inunison. A pair of cables 12 and 13 are each fixedly secured at one endto a drum 10, the other end of cable 12 extending downwardly from thedrum and being anchored by some suitable means, such as 14, to onecorner portion of the carriage. The other cable 13 extends substantiallyhorizontally from the drum 10, adjacent the brace beam 3, to and over adirection sheave 15 supported at the upper end of the post 1 at theother end of the frame, and thence downwardly and is secured to theadjacent corner portion of the carriage B. A similar pair of cables 12and 13 extend from the other drum l0 and are secured to and support theother two corners of the carriage structure.

- The reversible electric motor D is supported on the bracket extension16 of gear casing 16 adjacent the upper end of one of the posts 1. Themotor shaft 1? is connected through coupling 18 with the driving wormshaft 19 which meshes with worm wheel 20 and thence through the train ofgearing 21, 22, 23 and 24 drives one end of the winding drum assembly.The automatic friction brake mechanism indicated generally at 25 anddescribed more in detail in the Walker patent hereinabove referred to,serves as a safety brake for the winding mechanism and motor when theload is being lowered.

The switch mechanism indicated generally at E controls the reversiblemotor G. The switch mechanism is controlled by the rock shaft 26 on theouter end of which is secured the pointer and operating handle 27. Whenthe switch is in stop or neutral position, this member 27 will bepositioned horizontally as shown in Figs. 1, 8 and 9. To start the motorD for elevating the carriage, the member 27 is swung in a clockwisedirection through an angle of to the position shown in Fig. 6. To lowerthe carriage this member is swung through an angle of 90 in the oppositedirection as shown in Fig. '7.

The switch mechanism E is provided with mechanism as shown in Fig. 5 forautomatically throwing the switch to off or neutral position whenever amovement from either of its operative positions has been sufficientlystarted, and for yieldably holding the switch in each of its threeoperative positions. This mechanism will be positioned as shown in solidlines, Fig. 5, when the switch is in o or neutral position, and will bepositioned as shown in dotted lines when the switch is moved to eitherof its operating positions for causing the carriage to move either up ordown The cam member 28 is fixed to the shaft 26 and is formed in oneside with an arouate notch 29, and in its two ends with similar notches30 spaced further from the axis of the shaft than the central notch 29..The ends of notch 29 are connected with the respective notches 30 bythe inclined cam surfaces 31. The lever 32 pivoted at one end 83 to someconvenient fixed member (preferably within the switch housing 34)carries a roller 35 which is adapted to engage alternatively with one oranother of the notches 29 and 30 and with the cam surfaces 31. The lever32 is continuously urged in one direction so as to hold the roller 35against cam member 28 by means of spring 36 anchored at one end 37within housing 34 and secured at its other end to the free end of lever32. When the switch is in off or neutral position, spring 36 will holdroller 35 within notch 29 and thus yieldably hold the switch mechanismin this position. If switch member 2'7 is manually swung in onedirection or the other (that is to either of the positions shown inFigs. 6 or '7) the roller 35 will be forced out of notch 29 and alongone'of the cam surfaces 31 into one or the other of the end notches 30,whereupon spring 36 will snap the roller 35 into this notch 30 so as toyieldably hold the switch mechanism in the selected operative position.Now if the switch shaft 26 is moved, either manually orautomatically,.from this operative position sufficiently to move roller35 out of notch 30, the spring 36 will force the roller along the camsurface 31 so as to automatically throw the switch completely to itsneutral position and hold it in this position. As will be hereinafterapparent, this mechanism also functions to yieldably support, at times,a portion of the automatic stop mechanism in its elevated position.

A vertically shii'table switch-actuating plate 38 is guided for verticalsliding movement in the switch supporting bracket 39. The upper portionof this plate is offset at 40 (see Fig. so as to provide a verticallyextending socket 41 at the bottom of which is an upwardly facingshoulder 42 and-below which is a downwardly facing shoulder 43. Securedon the rock shaft 26 of the switch are an upwardly projecting arm orfinger 44 and a downwardly projecting arm or finger 45. When the switchis in off or neutral position, these fingers will be out of engagementwith the operating plate 38 as shown in Figs. 8 and 9. When the switchis rocked upwardly to cause the motor B to elevate the load, the finger44 will be swung into the socket 41 of plate 38 so as to be within thepath of upward movement of the shoulder 42. This position is shown inFig. 6 of the drawings. When the switch memmr is swung downwardly tolower the load, the finger 45 will be swung beneath the shoulder 43 ofplate 38 as shown in Fig. '7. This shiftable actuating plate 38 isautomatically moved in one direction or the other to engage one of thearms 44 or 45 and start the switch toward neutral position, thismovement of the switch being completed by the spring-actuated snapmechanism shown in Fig. 5 and already described.

This vertical actuating movement is imparted to plate 38 either by thelimit-stop mechanism indicated generally at G or by the slack-cablemechanism indicated generally at H. The limitstop mechanism G comprisesa vertically shiftable rod or bar 46 which is preferably housed withinthe hollow post 1 on which the switch E is mounted. The lower outwardlyturned end portion 47 of this rod projects through a vertical slot 48 inthe lower portion of the post so as to be in the path of movement of thecarriage guide 9, or some other adjacent portion of the carriage. Atransverse pin 49 holds this end of the rod in its outwardly projectedposition. The outwardly turned upper end portion 50 of this rod 46projects outwardly through a vertical slot 51 in the upper portion ofpost 1 and is anchored in a bracket member 52 having an arm 53 whichprojects downwardly along the outer side of the post to be engaged bythe upper surface of the carriage guide 9 as it nears its upper limit oftravel. A second arm 54 of this bracket member projects outwardly and issecured at 55 to the lower end portion of the switch-actuating plate 38,already described. This limit-stop mechanism, the operation of whichwill be hereinafterdescribed, has already been disclosed and claimed inthe patent to Willard T. Walker, 1,960,283, granted May 29, 1934.

The slack-cable stop mechanism H which forms, in combination withportions of the limitstop mechanism already described, the particularsubject matter of this invention, will now be described. A bracket plate56 is mounted on the switch assembly E (or some other convenient portionof the supporting frame), this plate being formed with an end flange 57and a bracket extension 58 in which is mounted the pivot pin 59. Aswinging frame comprising side lever arms 60 and 61 connected by theintermediate cross member 62 is mounted in bracket plate 56 by havingthe inner ends of the lever arms 60 and 61 pivoted on pin 59. A longroller 63 is mounted on pin 64 secured in the outer end portions oflever arms 60 and 61 pivoted on pin 59. The roller 63 is adapted to bearagainst the vertical run of cable 12. A torsion spring '65 is coiledabout pin 59 and has one end 66 engaging against supporting plate 56 andthe other end 67 bearing against the cross member 62 of the swingingframe. This spring 65 is of sufficient strength to swing the frame tothe position shown in Fig. 4 (in case cable 12 is slack) and to actuatethe stop mechanism in the manner hereinafter described. Under normalconditions, the swinging frame will be held down against the tension ofspring 65 by the taut cable 12 bearing against the roller 63 all asshown in Figs. 2 and 3. An operating finger 68, adapted to engage theupper end portion of the shiftable plate 38, is formed on the outer endof the lever or crank arm 69 formed on hub 70 journaled on one outer endportion of pin 59. A second lever arm 71 extending from this hub 70 isadjustably secured to the lever arm 61 of the swinging frame by means ofa clamping screw '72 mounted in arm 61 and extending through a slot 73in the arm 71. It will thus be noted that the operating finger 68 formsan extension of and moves with the swinging frame, but its positionrelative to the frame may be adjusted by means of screw '72. Normallythis finger 68 will be positioned adjacent to the path of verticalmovement of the upper end portion of plate 38, but out of engagementtherewith, as best shown in Figs. 6, 7 and 8.

' The operation of this entire stop mechanism will now best beunderstood by referring to the successive positions of the parts asshown in Figs. 1, 6, '7, 8 and 9. As shown in Fig. 8, the hoist has beencompletelylowered, the operating parts are all at rest, and the switchesin neutral position. However, although the carriage is at the lower endof its path of travel the hoisting cables are still taut and the slackcable device H is still held in inoperative position. At this time thelower end portion of rod 46 rests upon the supporting base 2 or upon thebase plate 74 at the lower end of post 1, so as to support the rod 46and switch actuating plate 38 in this lowermost position. In order toelevate the load, the switch member 27 is swung upwardly in a clockwisedirection through an angle of 90 to the position shown in Fig; 6. Thisbrings the operating finger 44 into the socket 41 of the plate 38 abovethe shoulder 42. As shown in Fig. 6, the carriage is traveling upwardlybut the. guide 9 has not yet engaged with the arm 53 of the stopmechanism. As the carriage nears its upper limit of travel the guide 9will engage the lower end of arm 53 and lift the rod 46 and actuatingplate 38 so as to bring the shoulder 42 of the plate into engagementwith finger 44 and swing the switch shaft back toward neutral position.When this movement has progressed far enough to move the roller 35 outof notch 30 and on to one of the camsurfaces 31, the switch will besnapped completely to off or neutral position by spring 36. The partswill now be positioned as shown in Fig. 1.

When the carriage is to be lowered, the switch member is swung throughan arc of 90 in a counter-clockwise direction so that the pointer 27will project downwardly as shown in Fig. '7. This will bring the finger45 on the switch shaft underneath the shoulder 43 on the operating plate38. As the carriage guide 9 moves downwardly it will no longer supportthe bracket 52, but the operating members of the stop mechanism will nowbe supported by the finger 45 on the switch shaft and the lockingmechanism shown in Fig. 5. This position of the parts is indicated inFig. '7. As the carriage nears its lower limit of travel, the guide 9will engage the outwardly projecting lower end portion 47 of 38downwardly so as to swing the finger 45 and switch shaft 26 back in aclockwise direction toward neutral position, and as soon as thismovement has progressed sufficiently to move the roller out of notch 30onto the cam surface 31 the switch will be snapped completely to itsneutral position. The carriage and motor will now be this movement ishalted the cables will be completely unwound and will commence to windback in the reverse direction. This might damage the mechanism and wouldcause an undesired elevating movement of the carriage. However, as soonas the weight of the carriage is no longer suspended from the cables,and the cable 12 becomes slack, the spring 65 will swing therollercarrying frame toward the cable thus swinging down the operatingfinger 68 into engagement with the upper end of operating plate 38 so asto move this plate downwardly and cause the switch to be thrown to itsstop position. This position of the parts is shown in Fig. 9.

If at any time when the motor is operating to unwind the cable, thecables should become slack, this stop mechanism will immediately operateto deenergize the motor and stop the winding mechanism. For example, ifthe cable 12 against which the roller 63 bears should break or becomedetached, the motor will be stopped.

If one of the other cables should break the carri'age will cant so as tocause the loop 9 to grip the post and stop the carriage, whereupon thecables will become slack and the motor will stop.

It will be understood that the limit-stop mechanism operates normallywhenever the carriage reaches its upper-or lower limits of travel, butthe slack cable portion H of the stop device is a safety mechanism andunder normal operating conditions will remain continuously in theinoperative position shown in Figs. 1, 6, 7 and 8'.

I claim:

1. In combination with a hoist comprising a supporting frame, acarriage, a winding mechanism, a cable extending from the windingmechanism to the carriage and normally supp rting a portion of thecarriage, a motor for operating the winding mechanism and a controlswitch for the motor movable from a neutral position in which the motoris at rest to alternative positions for causing the carriage to beraised or lowered, a stop mechanism comprising means normally tending tothrow the switch to neutral position, and a member engaging against arun of the cable and functioning to hold the last mentioned means ininoperative position as long as the cable is taut.

2. In combination with a hoist comprising a supporting frame, acarriage, a winding mechanism, a cable extending from the winding mecha-.nism to the carriage and normally supporting a neutral position to stopthe motor, an actuating member positioned adjacent the path of movementof the shiftable member and adapted to engage and move the shiftablemember to stop the motor, a spring normally tending to cause thisoperative movement of the actuating member, and a member engaging thecable and holding the actuating member in inoperative position againstthe tension of the spring as long as the cable is taut.

3. In combination with a hoist comprising a supporting frame, acarriage, a winding mechanism, a cable extending from the windingmechanism to the carriage and normally supporting a portion of thecarriage, a motor for operating the winding mechanism, and a controlswitch for the motor movable from a neutral position in which the motoris at rest to alternative positions for causing the carriage to beraised or lowered, a stop mechanism comprising a shiftable memberadapted to throw the switch to neutral position to stop the motor, alever pivotally mounted adjacent the shiftable member, an arm on thislever adapted to engage and move the shiftable member, a roller carriedby an arm of the lever and engaging the cable to hold the lever ininoperative position as long as the cable is taut, and a springtensioned toswing the lever when the cable is slack and cause the firstmentioned lever arm. to engage and move the shiftable member to stop themotor.

4. In combination with a hoist comprising a supporting frame, acarriage, a winding mechanism, a cable extending from the windingmechanism to the carriage and normally supporting a portion of thecarriage, a motor for operat: ing the winding mechanism, and a controlswitch for the motor movable from a neutral position in which the motoris at rest to alternative positions for causing the carriage to beraised or lowered, a stop mechanism comprising a shiftable memberadapted to throw the switch to neuarm to operate the shiftable memberand stop the motor when the cable is slack.

5. In combination with a hoist comprising a supporting frame, acarriage, a winding medanism, a cable extending from the windingmechanism to the carriage and normally supporting a portion of thecarriage, a motor for operating the winding mechanism, and a controlswitch for the motor movable from a neutral position in which the motoris at rest to alternative positions for causing the carriage to beraised or lowered, a stop mechanism comprising a shiftable memberadapted to throw the switch to neutral position to stop the motor, aswinging frame mounted adjacent the shiftable member, a roller ,mountedin the frame and engaging a vertical run of the cable at all times, aspring engaging the frame and holding the roller against the taut cable,and an arm adjustably positioned on the frame to engage and operate theshiftable member, the spring acting to swing the frame and cause the armto operate the shiftable member and stop the motor when the cable isslack.

6. In combination with a hoist comprising a supporting frame, acarriage, a winding mechanism, a cable extending from the windingmechanism to the carriage and normally supporting a portion of thecarriage, a motor for operating the winding mechanism, and a controlswitch for I the motor movable from a neutral position in which themotor is at rest to alternative positions for causing the carriage to beraised or lowered, a stop mechanism comprising a shiftable memberadapted to throw the switch to neutral position to stop the motor, meansfor moving the shiftable member to stop the motor as the carriage nearseither limit of its travel, an actuating member positioned adjacent thepath of movement of the shiftable member and adapted to engage and movethe shiftable member to stop the motor, a spring normally tending tocause this operative movement of the actuating member, and a memberengaging the cable and holding the actuating member in inoperativeposition against the tension of the spring as long as the cable is taut.r

7. In combination with a hoist comprising a supporting frame, acarriage, a winding mechanism, a cable extending from the windingmechanism to the carriage and normally supporting a portion of thecarriage, a motor for operating the winding mechanism, and a controlswitch for the motor movable from a neutral position in which the motoris at rest to alternative po-- sitions for causing the carriage to beraised or lowered, a stop mechanism comprising a shiftable memberadapted to throw the switch to neutral position to stop the motor, meansfor moving the shiftable member to stop the motor as the carriage nearsthe limit of its travel, a swinging frame mounted adjacent the shiftablemember, a roller mounted in the frame and engaging a vertical run of thecable at all times, a spring engaging the frame and vholding the rolleragainst the taut cable, and an arm on the frame positioned to engage andoperate the shiftable member, the spring acting to swing the frame andcause the arm to operate the shiftable member and stop the motor whenthe cable is slack.

8. In combination with a hoist comprising a supporting frame, acarriage, a winding mechanism, a cable extending from the windingmechanism to the carriage and normally supporting a portion of thecarriage, a motor for operating the winding mechanism, and a controlswitch for the motor movable from a neutral position in which the motoris at rest to alternative positions for causing the carriage to beraised or lowered, a stop mechanism comprising a shiftable memberadapted to throw the switch to neutral position to stop the motor, meansengaged by the carriage as it nears either limit of its travel formovingthe shiftable member to stop the motor, an actuating memberpositioned adjacent the path of movement of the shiftable member andadapted to engage and move the shiftable member to stop the motor, aspring normally tending to cause this operative movement of theactuating member, and a member engaging the cable and holding theactuating member in inoperative position against the tension of thespring as long as the cable is taut.

9. In combination with a hoist comprising a supporting frame, acarriage, a winding mechanism, a cable extending from the windingmechanism to the carriage and normally supporting a portion of thecarriage, a motorfor operating the winding mechanism, and a controlswitch for the motor movable from a neutral position in which the motoris at rest to alternative positions for causing the carriage to beraised or lowered, a stop mechanism comprising a shiftable memberadapted to throw the switch to neutral position to stop the motor, meansengaged by the carriage as it nears either limit of its travel formoving the shiftable member to stop the motor, a swinging frame mountedadjacent the shiftable member, a roller mounted in the frame andengaging a vertical run of the cable at all times, a spring engaging theframe and holding the roller against the taut cable, and an arm on theframe positioned to engage and operate the shiftable member, the springacting to swing the frame and cause the arm to operate the shiftablemember and stop the motorwhen the cable is slack.

10. The combination with a hoist comprising a supporting frame, avertically movable carriage, a winding mechanism, a cable extending fromthe winding mechanism to the carriage and normally supporting a portionof the carriage, a motor for operating the winding mechanism, a controlswitch for the motor comprising a member adapted to be swung in eitherdirection from a neutral position to initiate either a raising orlowering movement of the carriage, and means for yieldably holding theswitch member in its neutral or either of its motor actuating positions,an automatic stop mechanism comprising a shiftable member positionedadjacent the switch member and having an offset portion, a pair offingers on the switch member movable alternatively into the path ofmovement of the offset portion of the shiftable member as the switchmember is swung in one direction or the other from neutral position, ameans connected with the shiftable member and engaged by a portion ofthe carriage as the carriage nears either limit of its vertical travelto move the shiftable member and stop the motor, an actuating memberpositioned adjacent the path of movement of the shiftable member andadapted to engage and move the shiftable member to stop the motor, aspring normally tending to cause this operating movement of theactuating member, and a member engaging the cable and holding theactuating member in inoperative position against the tension of thespring as long as the cable is taut.

11. The combination with a hoist comprising a supporting frame, avertically movable carriage, a winding mechanism, a cable extending fromthe winding mechanism to the carriage and normally supporting a portionof the carriage, a motor for operating the winding mechanism, a controlswitch for the motor comprising a member adapted to be swung in eitherdirection from a neutral position to initiate either a raising orlowering movement of the carriage, and means for yieldably holding theswitch member in its neutral or either of its motor actuating positions,an automatic stop mechanism comprising a shiftable member positionedadjacent the switch member and having an offset portion, a pair offingers on the switch member movable alternatively into the path ofmovement of the offset portion of the shiftable member as the switchmember is swung in one direction or the other from neutral position, ameans connected with the shiftable member and engaged by a portion ofthe carriage as the carriage nears either limit of its vertical travelto move the shiftable member and stop the motor, an actuating devicenormally tending to throw the shiftable member to stop the motor, and amember engaging the cable and functioning to hold the actuating devicein inoperative position as long as the cable is taut.

12. The combination with a hoist comprising a supporting frame, avertically movable carriage, a winding mechanism, a cable extending fromthe winding mechanism to the carriage and normally supporting a portionof the carriage, a motor for operating the winding mechanism, a controlswitch for the motor comprising a member adapted to be swung in eitherdirection from a neutral position to initiate either a raising orlowering movement of the carriage, and means for yieldably holding theswitch member in its neutral or either of its motor actuatingpositions,an automatic stop mechanism comprising a shiftable member positionedadjacent the switch member and having an offset portion, a

pair of fingers on the switch member movable alternatively into the pathof movement of the offset portion of the shiftable member as the switchmember is swung in one direction or the other from neutral position, ameans connected with the shiftable member and engaged by a portion ofthe carriage as the carriage'nears either limit of its vertical travelto move the shiftable member and stop the motor, a lever pivotallymounted adjacent the shiftable member, an arm on this lever adapted toengage and move the shiftable member, a roller carried by an arm of thelever and engaging the cable to hold the lever in inoperative positionas long as the cable is taut, and a spring tensioned to swing the leverwhen the cable is slack and cause the first mentioned lever arm toengage and move the shiftable member and stop the motor.

13. The combination with a hoistv comprising a supporting frame, avertically movable carriage, a winding mechanism, a cable extending fromthe winding mechanism to the carriage and normally supporting a portionof the carriage, a motor for operating the winding mechanism, a controlswitch for the motor comprising a member adapted to be swung in eitherdirection from a neutral position to initiate either a raising orlowering movement .of the carriage, and means for yieldably holding theswitch member in its neutral or either of its motor actuating positions,

an automatic stop mechanism comprising a shift-' able member positionedadjacent the switch member and having an offset portion, a pair offingers on the switch member movable alternatively into the path ofmovement of the offset portion of the shiftable member as the switchmember is swung in one direction or the other from neutral position, ameans connected with the shiftable mem ber and engaged by a portion ofthe carriage as the carriage nears either limit of its vertical travelto move the shiftable member and stop the motor, a swinging framemounted adjacent the shiftable member, a roller-mounted in the frame andengaging a vertical run of the cable at all times, a spring engaging theframe and holding the roller against the taut cable, and an arm on theframe positioned to engage and operate the shiftable member, the springacting to swing the frame and cause the arm to operate the shiftablemember and stop the motor when the cable is slack.

14. The combination with a hoist comprising a supporting frame, avertically movable carriage, a winding mechanism, a cable extending fromthe winding mechanism to the carriage and normally supporting a portionof the carriage, a motor for operating the winding mechanism, a controlswitch for the motor comprising a member adapted to be swung in eitherdirection from a neutral position to initiate either a raising orlowering movement of the carriage, and means for yieldably holding theswitch member in its neutral or either of its motor-actuating positions,an automatic stop mechanism comprising a shiftable member positionedadjacent the switch member and having an offset portion,a pair offingers on the switch member movable alternatively into the path ofmovement of the offset portion of the shiftable member as the switchmember is swung in one direction or the other from neutral position, ameans connected with the shiftable member and engaged by a portion ofthe carriage as the carriage nears either limit of its vertical travelto move the shiftable member and stop the motor, a swinging framemounted adjacent the shiftable member, a roller mounted in the frame andengaging a vertical run of the cable at all times, a spring engaging theframe and holding the roller against the taut cable, and an armadjustably positioned on the frame to engage and operate the shiftablemember, the spring acting to swing the frame and cause the arm tooperate the shiftable member and stop the motor when the cable is slack.

15. In combination with a'hoisting device comprising a windingmechanism, a cable extending from the winding mechanism and normallyheld taut by the load to be raised or lowered, a motor for operating thewinding mechanism, and a control switch for the motor movable from aneutral position in which the motor is at rest to alternative positionsfor causing the winding mechanism to be rotated in one direction or theother, a stop mechanism comprising means normally tending to throw theswitch to neutral position, and a member engaging against a run of thecable and functioning to hold the last-mentioned means in inoperativeposition as long as the cable is taut..

16. In combination with a hoisting device comprising a windingmechanism, a cable extending from the winding mechanism and normallyheld taut by the load to be raised or lowered, a motor for operating thewinding mechanism, and a' control switch for the motor movable from aneutral position in which the motor is at rest to alternative positionsfor causing the winding mechanism to be rotated in one direction ortheother, a stop mechanism comprising spring actuated means normallytending to throw the switch to neutral position, and a member engagingagainst a run of the cable and functioning to hold the last mentionedmeans in inoperative position in opposition to the force of the springas long as the cable is taut.

JOSEPH J. MIZER.

